SDLfilter: Filtering Satellite-Derived Locations

Functions to filter GPS and/or Argos locations. The provided
filters remove temporal and spatial duplicates, fixes located at a given
height from estimated high tide line, and locations with high error as
proposed in Shimada et al. (2012) <doi:10.3354/meps09747> and
Shimada et al. (2016) <doi:10.1007/s00227-015-2771-0>.